Thermostat with epidemic control ventilation

ABSTRACT

A controller for controlling HVAC equipment in a building includes a processing circuit configured to receive an occupancy schedule indicating at least one of a first occupied period or a last unoccupied period for a space in the building for a schedule period and receive a user input indicating the space should be purged based on occupancy. The controller selects, based on the user input, at least one of a pre-occupancy purge mode or a post-occupancy purge mode. The controller is further configured to control the HVAC equipment to ventilate the space for a purge duration prior to the beginning of the first occupied period in response to selecting a pre-occupancy purge mode, and ventilate the space for the purge duration at the beginning of the last unoccupied period in response to selecting a post-occupancy purge mode.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 63/304,810, filed Jan. 31, 2022, which is incorporatedherein by reference in its entirety.

BACKGROUND

Heating, ventilating, or air conditioning (HVAC) systems forresidential, industrial, and commercial buildings often include acontroller, such as a thermostat, installed within the building tomonitor temperature and provide control signals to HVAC equipment. Thepresent invention relates generally to thermostats and more particularlyto improved control of a building or a space through the use of amulti-function thermostat to maximize air quality and energy efficiency.

Traditional thermostats sense the temperature of a system and controlcomponents of the HVAC in order to maintain a setpoint. A thermostat maybe designed to control a heating or cooling system or an airconditioner. Thermostats are manufactured in many ways, and use avariety of sensors to measure temperature and other desired parametersof a system.

Conventional thermostats are configured for one-way communication toconnected components, and to control HVAC systems by turning on or offcertain components or by regulating flow. Each thermostat may include atemperature sensor and a user interface. The user interface typicallyincludes a display for presenting information to a user and one or moreuser interface elements for receiving input from a user. To control thetemperature or other environmental parameters of a building or space, auser adjusts the space via the thermostat's user interface.

SUMMARY

Some embodiments of the present disclosure are related to a controllerfor controlling heating, ventilation, or air conditioning (HVAC)equipment in a building. The controller includes a processing circuitconfigured to receive an occupancy schedule indicating at least one of afirst occupied period or a last unoccupied period for a space in thebuilding for a schedule period and receive a user input indicating thespace should be purged based on occupancy. The controller is furtherconfigured to select, based on the user input, at least one of apre-occupancy purge mode or a post-occupancy purge mode. The controlleris further configured to control the HVAC equipment to ventilate thespace for a purge duration prior to the beginning of the first occupiedperiod in response to selecting a pre-occupancy purge mode, and controlthe HVAC equipment to ventilate the space for the purge duration at thebeginning of the last unoccupied period in response to selecting apost-occupancy purge mode.

Another exemplary embodiment relates to a method for operating acontroller for heating, ventilation, or air conditioning (HVAC)equipment in a building, the method including receiving an occupancyschedule indicating at least one of a first occupied period or a lastunoccupied period for a space in the building for a schedule period andreceiving a user input indicating the space should be purged based onoccupancy. The method further includes the steps of selecting, based onthe user input, at least one of a pre-occupancy purge mode or apost-occupancy purge mode. The method further includes controlling theHVAC equipment to ventilate the space for a purge duration prior to thebeginning of the first occupied period in response to selecting apre-occupancy purge mode and controlling the HVAC equipment to ventilatethe space for the purge duration at the beginning of the last unoccupiedperiod in response to selecting a post-occupancy purge mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, aspects, features, and advantages of the disclosurewill become more apparent and better understood by referring to thedetailed description taken in conjunction with the accompanyingdrawings, in which like reference characters identify correspondingelements throughout. In the drawings, like reference numbers generallyindicate identical, functionally similar, and/or structurally similarelements.

FIG. 1 is a schematic drawing of a building equipped with a HVAC system,according to an exemplary embodiment.

FIG. 2 is a schematic drawing of multiple zones and floors of thebuilding of FIG. 1 equipped with control devices, according to anexemplary embodiment.

FIG. 3 is a schematic block diagram of a waterside system that may beused in conjunction with the building of FIGS. 1-2 , according to anexemplary embodiment.

FIG. 4 is a schematic block diagram of an airside system that may beused in conjunction with the building of FIGS. 1-2 , according to anexemplary embodiment.

FIG. 5 is a schematic drawing of the connections of the control deviceof FIG. 2 and FIG. 4 , according to an exemplary embodiment.

FIG. 6 is a schematic diagram of a communications system located in thebuilding of FIGS. 1 and 2 , according to an exemplary embodiment.

FIG. 7 is a schematic block diagram illustrating the control device ofFIGS. 2, 4, 5, and 6 in greater detail, according to an exemplaryembodiment.

FIG. 8 is a perspective drawing of the control device of FIGS. 2, 4, 5,6, and 7 , according to an exemplary embodiment.

FIG. 9 is a schematic block diagram of a thermostat in a building,according to an exemplary embodiment.

FIG. 10 is a flowchart of a process for implementing demand controlventilation in a space, according to an exemplary embodiment.

FIG. 11 is a flowchart of a process for implementing epidemic controlventilation in a space, according to an exemplary embodiment.

FIG. 12 is a flowchart of a process for implementing an externalinterrupt in a building equipped with an HVAC system, according to anexemplary embodiment.

DETAILED DESCRIPTION Overview

Referring generally to the FIGURES, a thermostat for use in a heating,ventilation, or air conditioning (HVAC) system is shown. The thermostatdescribed herein may be used in any HVAC system, room, environment, orspace within which it is desired to control and/or observe environmentalconditions (e.g., temperature, humidity, CO₂ levels, etc.). A thermostatmay be adjusted by a user to control the environment in the space.

The thermostat can also control the environment in a space to reducepathogens that may be present in the space. The thermostat is intendedto provide the user with the ability to exchange the air in a space withfresh air from outside the building. When ventilating a space thethermostat can take into account the environmental conditions in thespace, its occupancy, and the environmental conditions outside of thespace.

In some embodiments, the thermostat provides the user with an ability tofunction as a connected smart hub. The thermostat provides a desirableuser interface for a smart hub with such environmental controls becauseof its known fixed location within a space and its ability to observeenvironmental conditions in the space.

The thermostat collects data about the space, its occupants, and theoutdoor air with various sensors (e.g., temperature sensors, humiditysensors, acoustic sensors, optical sensors, gas and other chemicalsensors, biometric sensors, motion sensors, etc.) and user inputs. Thethermostat may utilize data collected from a single room, multiplerooms, an entire building, or multiple buildings, and in some casesreceive data from other thermostat devices or supervisory devices. Thedata may be analyzed locally by the user control device or may beuploaded to a remote computing system and/or the cloud for furtheranalysis and processing.

Building Management System and HVAC System

Referring now to FIGS. 1-4 , an exemplary building management system(BMS) and HVAC system in which the systems and methods of the presentdisclosure may be implemented are shown, according to an exemplaryembodiment. Referring particularly to FIG. 1 , a perspective view of abuilding 10 is shown. Building 10 is served by a BMS. A BMS is, ingeneral, a system of devices configured to control, monitor, and manageequipment in or around a building or building area. A BMS can include,for example, a HVAC system, a security system, a lighting system, a firealerting system, and any other system that is capable of managingbuilding functions or devices, or any combination thereof.

The BMS that serves building 10 includes an HVAC system 100. HVAC system100 may include a plurality of HVAC devices (e.g., heaters, chillers,air handling units, pumps, fans, thermal energy storage, etc.)configured to provide heating, cooling, ventilation, or other servicesfor building 10. For example, HVAC system 100 is shown to include awaterside system 120 and an airside system 130. Waterside system 120 mayprovide a heated or chilled fluid to an air handling unit of airsidesystem 130. Airside system 130 may use the heated or chilled fluid toheat or cool an airflow provided to building 10. An exemplary watersidesystem and airside system which may be used in HVAC system 100 aredescribed in greater detail with reference to FIGS. 2-3 .

HVAC system 100 is shown to include a chiller 102, a boiler 104, and arooftop air handling unit (AHU) 106. Waterside system 120 may use boiler104 and chiller 102 to heat or cool a working fluid (e.g., water,glycol, etc.) and may circulate the working fluid to AHU 106. In variousembodiments, the HVAC devices of waterside system 120 may be located inor around building 10 (as shown in FIG. 1 ) or at an offsite locationsuch as a central plant (e.g., a chiller plant, a steam plant, a heatplant, etc.). The working fluid may be heated in boiler 104 or cooled inchiller 102, depending on whether heating or cooling is required inbuilding 10. Boiler 104 may add heat to the circulated fluid, forexample, by burning a combustible material (e.g., natural gas) or usingan electric heating element. Chiller 102 may place the circulated fluidin a heat exchange relationship with another fluid (e.g., a refrigerant)in a heat exchanger (e.g., an evaporator) to absorb heat from thecirculated fluid. The working fluid from chiller 102 and/or boiler 104may be transported to AHU 106 via piping 108.

AHU 106 may place the working fluid in a heat exchange relationship withan airflow passing through AHU 106 (e.g., via one or more stages ofcooling coils and/or heating coils). The airflow may be, for example,outside air, return air from within building 10, or a combination ofboth. AHU 106 may transfer heat between the airflow and the workingfluid to provide heating or cooling for the airflow. For example, AHU106 may include one or more fans or blowers configured to pass theairflow over or through a heat exchanger containing the working fluid.The working fluid may then return to chiller 102 or boiler 104 viapiping 110.

Airside system 130 may deliver the airflow supplied by AHU 106 (i.e.,the supply airflow) to building 10 via air supply ducts 112 and mayprovide return air from building 10 to AHU 106 via air return ducts 114.In some embodiments, airside system 130 includes multiple variable airvolume (VAV) units 116. For example, airside system 130 is shown toinclude a separate VAV unit 116 on each floor or zone of building 10.VAV units 116 may include dampers or other flow control elements thatcan be operated to control an amount of the supply airflow provided toindividual zones of building 10. In other embodiments, airside system130 delivers the supply airflow into one or more zones of building 10(e.g., via supply ducts 112) without using intermediate VAV units 116 orother flow control elements. AHU 106 may include various sensors (e.g.,temperature sensors, pressure sensors, etc.) configured to measureattributes of the supply airflow. AHU 106 may receive input from sensorslocated within AHU 106 and/or within the building zone and may adjustthe flow rate, temperature, or other attributes of the supply airflowthrough AHU 106 to achieve setpoint conditions for the building zone.

Referring now to FIG. 2 , building 10 is shown in greater detail,according to an exemplary embodiment. Building 10 may have multiplezones. In FIG. 2 , building 10 has zones, 202, 204, 206, 208, 210, and212. In building 10, the zones each correspond to a separate floor. Invarious embodiments, the zones of building 10 may be rooms, sections ofa floor, multiple floors, etc. Each zone may have a correspondingcontrol device 214. In some embodiments, control device 214 is at leastone of a thermostat, a sensor, a controller, a display device, aconcierge device, a medical monitor device, etc. Control device 214 maytake input from users. The input may be an environmental setpoint, aconcierge question, a payment, etc. In some embodiments, control device214 can cause music and/or building announcements to be played in one ormore of zones 202-212, cause the temperature and/or humidity to beregulated in one or more of zones 202-212, and/or any other controlaction.

In some embodiments, control device 214 can monitor the health of anoccupant 216 of building 10. In some embodiments, control device 214monitors heat signatures, heartrates, and any other information that canbe collected from cameras, medical devices, and/or any other healthrelated sensor. In some embodiments, building 10 has wirelesstransmitters 218 in each or some of zones 202-212. The wirelesstransmitters 218 may be routers, coordinators, and/or any other devicebroadcasting radio waves. In some embodiments, wireless transmitters 218form a Wi-Fi network, a Zigbee network, a Bluetooth network, and/or anyother kind of network.

In some embodiments, occupant 216 has a mobile device that cancommunicate with wireless transmitters 218. Control device 214 may usethe signal strengths between the mobile device of occupant 216 and thewireless transmitters 218 to determine in which zone the occupant is. Insome embodiments, control device 214 causes temperature setpoints, musicand/or other control actions to follow occupant 216 as the occupant 216moves from one zone to another zone (i.e., from one floor to anotherfloor).

In some embodiments, control devices 214 are connected to a buildingmanagement system, a weather server, and/or a building emergencysensor(s). In some embodiments, control devices 214 may receiveemergency notifications from the building management system, the weatherserver, and/or the building emergency sensor(s). Based on the nature ofthe emergency, control devices 214 may give directions to an occupant ofthe building. In some embodiments, the direction may be to respond to anemergency (e.g., call the police, hide and turn the lights off, etc.) Invarious embodiments, the directions given to the occupant (e.g.,occupant 216) may be navigation directions. For example, zone 212 may bea safe zone with no windows an individual (e.g., occupant 216). Ifcontrol devices 214 determines that there are high winds around building10, the control device 214 may direct occupants of zones 202-210 to zone212 if zone 212 has no windows.

Referring now to FIG. 3 , a block diagram of a waterside system 300 isshown, according to an exemplary embodiment. In various embodiments,waterside system 300 may supplement or replace waterside system 120 inHVAC system 100 or may be implemented separate from HVAC system 100.When implemented in HVAC system 100, waterside system 300 may include asubset of the HVAC devices in HVAC system 100 (e.g., boiler 104, chiller102, pumps, valves, etc.) and may operate to supply a heated or chilledfluid to AHU 106. The HVAC devices of waterside system 300 may belocated within building 10 (e.g., as components of waterside system 120)or at an offsite location such as a central plant.

In FIG. 3 , waterside system 300 is shown as a central plant having aplurality of subplants 302-312. Subplants 302-312 are shown to include aheater subplant 302, a heat recovery chiller subplant 304, a chillersubplant 306, a cooling tower subplant 308, a hot thermal energy storage(TES) subplant 310, and a cold thermal energy storage (TES) subplant312. Subplants 302-312 consume resources (e.g., water, natural gas,electricity, etc.) from utilities to serve the thermal energy loads(e.g., hot water, cold water, heating, cooling, etc.) of a building orcampus. For example, heater subplant 302 may be configured to heat waterin a hot water loop 314 that circulates the hot water between heatersubplant 302 and building 10. Chiller subplant 306 may be configured tochill water in a cold water loop 316 that circulates the cold waterbetween chiller subplant 306 building 10. Heat recovery chiller subplant304 may be configured to transfer heat from cold water loop 316 to hotwater loop 314 to provide additional heating for the hot water andadditional cooling for the cold water. Condenser water loop 318 mayabsorb heat from the cold water in chiller subplant 306 and reject theabsorbed heat in cooling tower subplant 308 or transfer the absorbedheat to hot water loop 314. Hot TES subplant 310 and cold TES subplant312 may store hot and cold thermal energy, respectively, for subsequentuse.

Hot water loop 314 and cold water loop 316 may deliver the heated and/orchilled water to air handlers located on the rooftop of building 10(e.g., AHU 106) or to individual floors or zones of building 10 (e.g.,VAV units 116). The air handlers push air past heat exchangers (e.g.,heating coils or cooling coils) through which the water flows to provideheating or cooling for the air. The heated or cooled air may bedelivered to individual zones of building 10 to serve the thermal energyloads of building 10. The water then returns to subplants 302-312 toreceive further heating or cooling.

Although subplants 302-312 are shown and described as heating andcooling water for circulation to a building, it is understood that anyother type of working fluid (e.g., glycol, CO2, etc.) may be used inplace of or in addition to water to serve the thermal energy loads. Inother embodiments, subplants 302-312 may provide heating and/or coolingdirectly to the building or campus without requiring an intermediateheat transfer fluid. These and other variations to waterside system 300are within the teachings of the present disclosure.

Each of subplants 302-312 may include a variety of equipment configuredto facilitate the functions of the subplant. For example, heatersubplant 302 is shown to include a plurality of heating elements 320(e.g., boilers, electric heaters, etc.) configured to add heat to thehot water in hot water loop 314. Heater subplant 302 is also shown toinclude several pumps 322 and 324 configured to circulate the hot waterin hot water loop 314 and to control the flow rate of the hot waterthrough individual heating elements 320. Chiller subplant 306 is shownto include a plurality of chillers 332 configured to remove heat fromthe cold water in cold water loop 316. Chiller subplant 306 is alsoshown to include several pumps 334 and 336 configured to circulate thecold water in cold water loop 316 and to control the flow rate of thecold water through individual chillers 332.

Heat recovery chiller subplant 304 is shown to include a plurality ofheat recovery heat exchangers 326 (e.g., refrigeration circuits)configured to transfer heat from cold water loop 316 to hot water loop314. Heat recovery chiller subplant 304 is also shown to include severalpumps 328 and 330 configured to circulate the hot water and/or coldwater through heat recovery heat exchangers 326 and to control the flowrate of the water through individual heat recovery heat exchangers 226.Cooling tower subplant 308 is shown to include a plurality of coolingtowers 338 configured to remove heat from the condenser water incondenser water loop 318. Cooling tower subplant 308 is also shown toinclude several pumps 340 configured to circulate the condenser water incondenser water loop 318 and to control the flow rate of the condenserwater through individual cooling towers 338.

Hot TES subplant 310 is shown to include a hot TES tank 342 configuredto store the hot water for later use. Hot TES subplant 310 may alsoinclude one or more pumps or valves configured to control the flow rateof the hot water into or out of hot TES tank 342. Cold TES subplant 312is shown to include cold TES tanks 344 configured to store the coldwater for later use. Cold TES subplant 312 may also include one or morepumps or valves configured to control the flow rate of the cold waterinto or out of cold TES tanks 344.

In some embodiments, one or more of the pumps in waterside system 300(e.g., pumps 322, 324, 328, 330, 334, 336, and/or 340) or pipelines inwaterside system 300 include an isolation valve associated therewith.Isolation valves may be integrated with the pumps or positioned upstreamor downstream of the pumps to control the fluid flows in watersidesystem 300. In various embodiments, waterside system 300 may includemore, fewer, or different types of devices and/or subplants based on theparticular configuration of waterside system 300 and the types of loadsserved by waterside system 300.

Referring now to FIG. 4 , airside system 400 is shown to include aneconomizer-type air handling unit (AHU) 402. Economizer-type AHUs varythe amount of outside air and return air used by the air handling unitfor heating or cooling. For example, AHU 402 may receive return air 404from building zone 406 via return air duct 408 and may deliver supplyair 410 to building zone 406 via supply air duct 412. In someembodiments, AHU 402 is a rooftop unit located on the roof of building10 (e.g., AHU 402 as shown in FIG. 1 ) or otherwise positioned toreceive both return air 404 and outside air 414. AHU 402 may beconfigured to operate exhaust air damper 416, mixing damper 418, andoutside air damper 420 to control an amount of outside air 414 andreturn air 404 that combine to form supply air 410. Any return air 404that does not pass through mixing damper 418 may be exhausted from AHU402 through exhaust damper 416 as exhaust air 422.

Each of dampers 416-420 may be operated by an actuator. For example,exhaust air damper 416 may be operated by actuator 424, mixing damper418 may be operated by actuator 426, and outside air damper 420 may beoperated by actuator 428. Actuators 424-428 may communicate with an AHUcontroller 430 via a communications link 432. Actuators 424-428 mayreceive control signals from AHU controller 430 and may provide feedbacksignals to AHU controller 430. Feedback signals may include, forexample, an indication of a current actuator or damper position, anamount of torque or force exerted by the actuator, diagnosticinformation (e.g., results of diagnostic tests performed by actuators424-428), status information, commissioning information, configurationsettings, calibration data, and/or other types of information or datathat may be collected, stored, or used by actuators 424-428. AHUcontroller 430 may be an economizer controller configured to use one ormore control algorithms (e.g., state-based algorithms, extremum seekingcontrol (ESC) algorithms, proportional-integral (PI) control algorithms,proportional-integral-derivative (PID) control algorithms, modelpredictive control (MPC) algorithms, feedback control algorithms, etc.)to control actuators 424-428.

Still referring to FIG. 4 , AHU 402 is shown to include a cooling coil434, a heating coil 436, and a fan 438 positioned within supply air duct412. Fan 438 may be configured to force supply air 410 through coolingcoil 434 and/or heating coil 436 and provide supply air 410 to buildingzone 406. AHU controller 430 may communicate with fan 438 viacommunications link 440 to control a flow rate of supply air 410. Insome embodiments, AHU controller 430 controls an amount of heating orcooling applied to supply air 410 by modulating a speed of fan 438.

Cooling coil 434 may receive a chilled fluid from waterside system 200(e.g., from cold water loop 316) via piping 442 and may return thechilled fluid to waterside system 200 via piping 444. Valve 446 may bepositioned along piping 442 or piping 444 to control a flow rate of thechilled fluid through cooling coil 474. In some embodiments, coolingcoil 434 includes multiple stages of cooling coils that can beindependently activated and deactivated (e.g., by AHU controller 430, byBMS controller 466, etc.) to modulate an amount of cooling applied tosupply air 410.

Heating coil 436 may receive a heated fluid from waterside system 200(e.g., from hot water loop 314) via piping 448 and may return the heatedfluid to waterside system 200 via piping 450. Valve 452 may bepositioned along piping 448 or piping 450 to control a flow rate of theheated fluid through heating coil 436. In some embodiments, heating coil436 includes multiple stages of heating coils that can be independentlyactivated and deactivated (e.g., by AHU controller 430, by BMScontroller 466, etc.) to modulate an amount of heating applied to supplyair 410.

Each of valves 446 and 452 may be controlled by an actuator. Forexample, valve 446 may be controlled by actuator 454 and valve 452 maybe controlled by actuator 456. Actuators 454-456 may communicate withAHU controller 430 via communications links 458-460. Actuators 454-456may receive control signals from AHU controller 430 and may providefeedback signals to controller 430. In some embodiments, AHU controller430 receives a measurement of the supply air temperature from atemperature sensor 462 positioned in supply air duct 412 (e.g.,downstream of cooling coil 434 and/or heating coil 436). AHU controller430 may also receive a measurement of the temperature of building zone406 from a temperature sensor 464 located in building zone 406.

In some embodiments, AHU controller 430 operates valves 446 and 452 viaactuators 454-456 to modulate an amount of heating or cooling providedto supply air 410 (e.g., to achieve a set point temperature for supplyair 410 or to maintain the temperature of supply air 410 within a setpoint temperature range). The positions of valves 446 and 452 affect theamount of heating or cooling provided to supply air 410 by cooling coil434 or heating coil 436 and may correlate with the amount of energyconsumed to achieve a desired supply air temperature. AHU controller 430may control the temperature of supply air 410 and/or building zone 406by activating or deactivating coils 434-436, adjusting a speed of fan438, or a combination of both.

Still referring to FIG. 4 , airside system 400 is shown to include abuilding management system (BMS) controller 466 and a control device214. BMS controller 466 may include one or more computer systems (e.g.,servers, supervisory controllers, subsystem controllers, etc.) thatserve as system level controllers, application or data servers, headnodes, or master controllers for airside system 400, waterside system200, HVAC system 100, and/or other controllable systems that servebuilding 10. BMS controller 466 may communicate with multiple downstreambuilding systems or subsystems (e.g., HVAC system 100, a securitysystem, a lighting system, waterside system 200, etc.) via acommunications link 470 according to like or disparate protocols (e.g.,LON, BACnet, etc.). In various embodiments, AHU controller 430 and BMScontroller 466 may be separate (as shown in FIG. 4 ) or integrated. Inan integrated implementation, AHU controller 430 may be a softwaremodule configured for execution by a processor of BMS controller 466.

In some embodiments, AHU controller 430 receives information from BMScontroller 466 (e.g., commands, set points, operating boundaries, etc.)and provides information to BMS controller 466 (e.g., temperaturemeasurements, valve or actuator positions, operating statuses,diagnostics, etc.). For example, AHU controller 430 may provide BMScontroller 466 with temperature measurements from temperature sensors462-464, equipment on/off states, equipment operating capacities, and/orany other information that can be used by BMS controller 466 to monitoror control a variable state or condition within building zone 406.

Control device 214 may include one or more of the user control devices.Control device 214 may include one or more human-machine interfaces orclient interfaces (e.g., graphical user interfaces, reportinginterfaces, text-based computer interfaces, client-facing web services,web servers that provide pages to web clients, etc.) for controlling,viewing, or otherwise interacting with HVAC system 100, its subsystems,and/or devices. Control device 214 may be a computer workstation, aclient terminal, a remote or local interface, or any other type of userinterface device. Control device 214 may be a stationary terminal or amobile device. For example, control device 214 may be a desktopcomputer, a computer server with a user interface, a laptop computer, atablet, a smartphone, a PDA, or any other type of mobile or non-mobiledevice. Control device 214 may communicate with BMS controller 466and/or AHU controller 430 via communications link 472. In someembodiments, control device 214 communicates directly with AHUcontroller 430, bypassing BMS controller 466.

Referring now to FIG. 5 , control device 214 is shown as a connectedsmart hub or private area network (PAN), according to some embodiments.Control device 214 may include a variety of sensors and may beconfigured to communicate with a variety of external systems or devices.For example, control device 214 may include temperature sensors 502,speakers 504, leak detection system 508, health monitoring sensors 510,humidity sensors 514, occupancy sensors 516, light detection sensors518, proximity sensor 520, carbon dioxide sensors 522, or any of avariety of other sensors. Alternatively, control device 214 may receiveinput from external sensors configured to measure such variables. Theexternal sensors may not communicate over a PAN network but maycommunicate with control device 214 via an IP based network and/or theInternet.

In some embodiments, speakers 504 are located locally as a component ofcontrol device 214. Speakers 504 may be low power speakers used forplaying audio to the immediate occupant of control device 214 and/oroccupants of the zone in which control device 214 is located. In someembodiments, speakers 504 may be remote speakers connected to controldevice 214 via a network. In some embodiments, speakers 504 are abuilding audio system, an emergency alert system, and/or alarm systemconfigured to broadcast building wide and/or zone messages or alarms.

Control device 214 may communicate with a remote camera 506, a shadecontrol system 512, a leak detection system 508, a HVAC system, or anyof a variety of other external systems or devices which may be used in ahome automation system or a building automation system. Control device214 may provide a variety of monitoring and control interfaces to allowa user to control all of the systems and devices connected to controldevice 214. Exemplary user interfaces and features of control device 214are described in greater detail below.

Referring now to FIG. 6 , a block diagram of communications system 600is shown, according to an exemplary embodiment. System 600 can beimplemented in a building (e.g. building 10) and is shown to includecontrol device 214, network 602, healthcare sensor(s) 604, buildingemergency sensor(s) 606, weather server(s) 608, building managementsystem 610, and user device 612. System 600 connects devices, systems,and servers via network 602 so that building information, HVAC controls,emergency information, navigation directions, and other information canbe passed between devices (e.g., control device 214, user device 612,and/or building emergency sensor(s) 606 and servers and systems (e.g.,weather server(s) 608 and/or building management system 610). In someembodiments, control device 214 is connected to speakers 504 asdescribed with reference to FIG. 5 .

In some embodiments, network 602 communicatively couples the devices,systems, and servers of system 600. In some embodiments, network 602 isat least one of and/or a combination of a Wi-Fi network, a wiredEthernet network, a ZigBee network, and a Bluetooth network. Network 602may be a local area network or a wide area network (e.g., the Internet,a building WAN, etc.) and may use a variety of communications protocols(e.g., BACnet, IP, LON, etc.) Network 602 may include routers, modems,and/or network switches. The devices in system 600 including the controldevice 214 can include a software interface such as Open Blue Bridgelive connection between the physical and digital replicas, enabling dataexchange for seamless communication and action. The software interfacecan be executed on processing platform on the edge device (e.g., controldevice 214) and provide digital twinning on the control device forcontrol device 214 and other sensors or equipment in system 600. Thesoftware interface also allows artificial intelligence (AI) applicationto be executed in the edge device and perform data analytics. Dataanalytics and a software interface are discussed in U.S. applicationSer. No. 17/134,691, filed Dec. 28, 2020, incorporated herein byreference in its entirety and assigned to the assignee of the presentapplication.

In some embodiments, control device 214 is configured to receiveemergency information, navigation directions, occupant information,concierge information, and any other information via network 602. Insome embodiments, the information is received from building managementsystem 610 via network 602. In various embodiments, the information isreceived from the Internet via network 602. In some embodiments, controldevice 214 is at least one of or a combination of a thermostat, ahumidistat, a light controller, and any other wall mounted and/or handheld device. In some embodiments, control device 214 is connected tobuilding emergency sensor(s) 606. In some embodiments, buildingemergency sensor(s) 606 are sensors which detect building emergencies.Building emergency sensor(s) 606 may be smoke detectors, carbon monoxidedetectors, carbon dioxide detectors (e.g., carbon dioxide sensors 522),an emergency button (e.g., emergency pull handles, panic buttons, amanual fire alarm button and/or handle, etc.) and/or any other emergencysensor. In some embodiments, the emergency sensor(s) include actuators.The actuators may be building emergency sirens and/or building audiospeaker systems (e.g., speakers 504), automatic door and/or windowcontrol (e.g., shade control system 512), and any other actuator used ina building.

In some embodiments, control device 214 may be communicatively coupledto weather server(s) 608 via network 602. In some embodiments, thecontrol device 214 may be configured to receive weather alerts (e.g.,high and low daily temperature, five-day forecast, thirty-day forecast,etc.) from weather server(s) 608. Control device 214 may be configuredto receive emergency weather alerts (e.g., flood warnings, firewarnings, thunder storm warnings, winter storm warnings, etc.) In someembodiments, control device 214 may be configured to display emergencywarnings via a user interface of control device 214 when control device214 receives an emergency weather alert from weather server(s) 608. Thecontrol device 214 may be configured to display emergency warnings basedon the data received from building emergency sensor(s) 606. In someembodiments, the control device 214 may cause a siren (e.g., speakers504 and/or building emergency sensor(s) 606) to alert occupants of thebuilding of an emergency, cause all doors to become locked and/orunlocked, cause an advisory message be broadcast through the building,and control any other actuator or system necessary for responding to abuilding emergency.

In some embodiments, control device 214 is configured to communicatewith building management system 610 via network 602. Control device 214may be configured to transmit environmental setpoints (e.g., temperaturesetpoint, humidity setpoint, etc.) to building management system 610. Insome embodiments, building management system 610 may be configured tocause zones of a building (e.g., building 10) to be controlled to thesetpoint received from control device 214. In some embodiments, buildingmanagement system 610 may be configured to control the lighting of abuilding. In some embodiments, building management system 610 may beconfigured to transmit emergency information to control device 214. Insome embodiments, the emergency information is a notification of ashooter lockdown, a tornado warning, a flood warning, a thunderstormwarning, and/or any other warning. In some embodiments, buildingmanagement system 610 is connected to various weather servers or otherweb servers from which building management system 610 receives emergencywarning information. In various embodiments, building management systemis a computing system of a hotel. Building management system 610 maykeep track of hotel occupancy, may relay requests to hotel staff, and/orperform any other functions of a hotel computing system.

Control device 214 can be configured to communicate with user device 612via network 602. In some embodiments, user device 612 is a smartphone, atablet, a laptop computer, and/or any other mobile and/or stationarycomputing device. In some embodiments, user device 612 communicatescalendar information to control device 214. In some embodiments, thecalendar information is stored and/or entered by a user into a calendarapplication. In some embodiments, calendar application is at least oneof Outlook, Google Calendar, Fantastical, Shifts, CloudCal, DigiCal,and/or any other calendar application. In some embodiments, controldevice 214 receives calendar information from the calendar applicationsuch as times and locations of appointments, times and locations ofmeetings, and/or any other information. Control device 214 may beconfigured to display building map direction to a user associated withuser device 612 and/or any other information.

In some embodiments, a user may press a button on a user interface ofcontrol device 214 indicating a building emergency. The user may be ableto indicate the type of emergency (e.g., fire, flood, active shooter,etc.) Control device 214 may communicate an alert to building managementsystem 610, user device 612, and any other device, system, and/orserver.

In some embodiments, control device 214 is communicably coupled tohealthcare sensor(s) 604 via network 602. In some embodiments, controldevice 214 is configured to monitor healthcare sensor(s) 604 collectingdata for occupants of a building (e.g., building 10) and determinehealth metrics for the occupants based on the data received from thehealthcare sensor(s) 604. In some embodiments, healthcare sensor(s) 604are one or more smart wrist bands, pacemakers, insulin pumps, and/or anyother medical device. The health metrics may be determined based onheart rates, insulin levels, and/or any other biological and/or medicaldata.

In some embodiments, user device 612 is configured to provide one ortemplates for storage on control device 214. The templates define iconsand locations as well as location for text information on controldevice. The templates are created in application software for the userdevice 612 (e.g., a mobile device, cell phone, etc.). In someembodiments, backgrounds for each templates can be selected. Templatesinclude logo templates including customer or supplier logos and non-logotemplates. Templates can be selected for specific buildings, rooms,environments (e.g., hospital, store, hotel, home, etc.) Some templatesmay be created for visually impaired or for different languages. Sometemplates may be for carbon emission/footprint monitoring, measuring,scoring (e.g. versus others, standards, or targets), and include iconsdedicated to these applications (e.g., a green leaf having a sizeindicating green compliance, air quality warnings and icons indicatingair quality, sustainability icons and settings, etc.).

Referring now to FIG. 7 , a block diagram illustrating control device214 in greater detail is shown, according to some embodiments. Controldevice 214 is shown to include a variety of user interfaces 702 andsensors 714 and is embodied as a commercial or residential thermostat.User interfaces 702 may be configured to receive input from a user andprovide output to a user in various forms. For example, user interfaces702 are shown to include touch-sensitive panel 704, electronic display706 (e.g., pixelated display), ambient lighting 708, speakers 710 (e.g.,speakers 504), and input device 712. In some embodiments, userinterfaces 702 include a microphone configured to receive voice commandsfrom a user, a keyboard or buttons, switches, dials, or any otheruser-operable input devices. It is contemplated that user interfaces 702may include any type of device configured to receive input from a userand/or provide an output to a user in any of a variety of forms (e.g.,touch, text, video, graphics, audio, vibration, etc.).

Sensors 714 may be configured to measure a variable state or conditionof the environment in which control device 214 is installed. Forexample, sensors 714 are shown to include a temperature sensor 716, ahumidity sensor 718, an ambient light sensor 719, an air quality sensor720, a proximity sensor 722, a camera 724, a microphone 726, a lightsensor 728, and a vibration sensor 730. In some embodiments, one or moreof sensors 714 is not provided (e.g., microphone 726 and camera 724).Air quality sensor 720 may be configured to measure any of a variety ofair quality variables such as oxygen level, carbon dioxide (CO₂) level,carbon monoxide level, allergens, pollutants, smoke, etc. Proximitysensor 722 may include one or more sensors configured to detect thepresence of people or devices proximate to control device 214. Forexample, proximity sensor 722 may include a near-field communications(NFC) sensor, a radio frequency identification (RFID) sensor, aBluetooth sensor, a capacitive proximity sensor, a biometric sensor, aninfrared sensor, or any other sensor configured to detect the presenceof a person or device. Camera 724 may include a visible light camera, amotion detector camera, an infrared camera, an ultraviolet camera, anoptical sensor, or any other type of camera. Light sensor 728 may beconfigured to measure ambient light levels. Vibration sensor 730 may beconfigured to measure vibrations from earthquakes or other seismicactivity at the location of control device 214.

Still referring to FIG. 7 , control device 214 is shown to include acommunications interface 732 and a processing circuit 734.Communications interface 732 may include wired or wireless interfaces(e.g., jacks, antennas, transmitters, receivers, transceivers, wireterminals, etc.) for conducting data communications with varioussystems, devices, or networks. For example, communications interface 732may include an Ethernet card and port for sending and receiving data viaan Ethernet-based communications network and/or a Wi-Fi transceiver forcommunicating via a wireless communications network. Communicationsinterface 732 may be configured to communicate via local area networksor wide area networks (e.g., the Internet, a building WAN, etc.) and mayuse a variety of communications protocols (e.g., BACnet, IP, LON, etc.).

Communications interface 732 may include a network interface configuredto facilitate electronic data communications between control device 214and various external systems or devices (e.g., network 602, buildingmanagement system 610, HVAC equipment 738, user device 612, etc.) Forexample, control device 214 may receive information from buildingmanagement system 610 or HVAC equipment 738 indicating one or moremeasured states of the controlled building (e.g., temperature, humidity,electric loads, etc.) and one or more states of the HVAC equipment 738(e.g., equipment status, power consumption, equipment availability,etc.). In some embodiments, HVAC equipment 738 may be lighting systems,building systems, actuators, chillers, heaters, and/or any otherbuilding equipment and/or system. The communication interface 732between HVAC equipment 738 is a three wire (power, ground acommunication) or four wire (power, communication 1, communication 2,and ground, B, G, Y, R or W or O/B, C, K, R) connection in someembodiments. Communications interface 732 may receive inputs frombuilding management system 610 or HVAC equipment 738 and may provideoperating parameters (e.g., on/off decisions, set points, etc.) tobuilding management system 610 or HVAC equipment 738. The operatingparameters may cause building management system 610 to activate,deactivate, or adjust a set point for various types of home equipment orbuilding equipment in communication with control device 214.

Processing circuit 734 is shown to include a processor 740 and memory742. Processor 740 may be a general purpose or specific purposeprocessor, an application specific integrated circuit (ASIC), one ormore field programmable gate arrays (FPGAs), a group of processingcomponents, or other suitable processing components. Processor 740 maybe configured to execute computer code or instructions stored in memory742 or received from other computer readable media (e.g., CDROM, networkstorage, a remote server, etc.). Processing circuit 734 adjusts thebrightness of the electronic display 706 based upon ambient light sensedby ambient light sensor 719 or weather information received via network602.

Memory 742 may include one or more devices (e.g., memory units, memorydevices, storage devices, etc.) for storing data and/or computer codefor completing and/or facilitating the various processes described inthe present disclosure. Memory 742 may include random access memory(RAM), read-only memory (ROM), hard drive storage, temporary storage,non-volatile memory, flash memory, optical memory, or any other suitablememory for storing software objects and/or computer instructions. Asused herein, memory excludes any transitory signals. Memory 742 mayinclude database components, object code components, script components,or any other type of information structure for supporting the variousactivities and information structures described in the presentdisclosure. Memory 742 may be communicably connected to processor 740via processing circuit 734 and may include computer code for executing(e.g., by processor 740) one or more processes described herein. Forexample, memory 742 includes a ventilation module 744, a purge module746, an external interrupt module 748, and an occupancy module 750. Theoperation of some of these modules is described in greater detail below.

In some embodiments, ventilation module 744, purge module 746, andexternal interrupt module 748 are user configurable, for example at thecontrol device 214 itself. When connected to a BMS (e.g., via BMScontroller 466), a user of the BMS may also configure ventilation module744, purge module 746, and external interrupt module 748 remotely viaBMS interface. In some embodiments, a user may configure one or moremodules via an app on a mobile device (e.g., user device 612 of FIG. 6).

LED module 748 controls light output 749 (e.g., LED output) to provide alight associated with an operating mode (idle, heat, cool. oremergency). The light output 749 can provide a color, flash, strobe inpattern, etc. to indicate a condition. For example, a red color canindicate a heat mode, a blue color can indicate a cool mode, a flashingorange can indicate an emergency or fault, and white or yellow canindicate an idle mode. Based on message received from the network orinternal logic, user can configure the color of the light output 749(e.g., one or more LEDs) and flashing pattern. For example, when it is atime to replace a filter, the light output 749 turns Yellow and flashesat constant or configurable interval or if there is a message from thefacility manager to control device 214 and the message is not read yet,the light output 749 turns cyan.

The light output 749 includes one or more color light emitting diodes insome embodiments. Processing circuit 734 also controls displaybrightness in response to signals from ambient light sensor 719, time ofday/season and/or weather information received from network 602.

Referring now to FIG. 8 , a perspective view schematic of the controldevice 214 of FIG. 7 is shown, according to an exemplary embodiment. Thecontrol device 214 includes one or more sensors 714 (e.g., humidity 718,proximity 722, etc.) on an upper right corner of the face of the controldevice 214. Additional sensors may be included inside the control device214 and/or positioned at other locations. The user interface 702includes an electronic display 706 (which may itself include or bepositioned behind a touch-sensitive panel 704, not shown). In variousembodiments, the control device 214 provides visual indicia of theoperating modes, the setpoints, and the indoor or outdoor temperature,the CO₂ value, and the position of the damper on the user interface 702.For example, the user interface 702 may display the CO₂ value of thespace, the damper position, and/or notifications is presented to a userof control device 214 in display areas 754, 756, and 758.

Air Quality Control

Referring generally to FIGS. 9-11 , a thermostat may be configured tocontrol the air quality in a space or building. Indoor air is often morecontaminated than outdoor air, and the contaminants can includepathogens, contagions, and other disease-causing agents that may passfrom one occupant to another. Over time, the concentrations of pathogensin the space can increase and without sufficient ventilation space thereis an greater chance occupants infect one another. The regular exchangeof indoor air with outdoor air can reduce the concentration of suchpathogens in a space. A thermostat can be configured to perform such anair exchange periodically and/or on-demand using the cleaner outdoor airto assist in removing the concentration of airborne infectious particlesand protect the health of the occupants.

In some embodiments, the thermostat can modulate one or more dampers inHVAC equipment (e.g., outside air damper 420 of AHU 402) to control theintake of outdoor airflow into the space and exchange clean outdoor airfor indoor air. The HVAC equipment may include economizer-type airhandling units (e.g., AHU 402) with a return air intake configured toreceive return air from within a building, an outdoor air intakeconfigured to receive outdoor air from outside the building, and an airdischarge configured to provide discharge air to the building. In someembodiments, the economizer-type AHU includes one or more dampers (e.g.,dampers 416-420) whose position may be modulated to control the sourcesand flow of air into a space. The position of a damper may include afully closed position at 0% and a fully open position at 100%, withintermediate positions in-between. In some embodiments, the minimumventilator position is set by a user and may be between 0%-100%. An opendamper allows air to pass through the system.

In some embodiments, the thermostat can be configured to ventilate aspace based on one or more indoor air quality (IAQ) values in a space.The indoor air quality values may include concentrations of gasses orparticles in a space (e.g., pollutants, pathogens, etc.) and/or othermeasurable air quality parameters. Pollutants may include carbondioxide, carbon monoxide, nitrogen, radon, lead, asbestos, indoorparticulate matter, volatile organic compounds, etc. For example, thethermostat may be configured to take in fresh outdoor air in order tomaintain the space CO₂ value at or below a CO₂ setpoint. The CO₂ valueof a space can be used as an indirect measurement of the occupancy stateof a space and the concentration of airborne infectious particles.Higher CO₂ values indicate increased occupancy and likely higherconcentrations of other occupant byproducts such as pathogens. Thethermostat can control the rate of outdoor air into the space when theCO₂ value breaches the setpoint, and exchange the indoor air in thespace with outdoor air, lowering not only the CO₂ value of the space butalso the concentration of the infectious particles.

In some embodiments, the thermostat additionally controls the rate ofoutdoor airflow into the space based in part on whether the space isoccupied or unoccupied. For example, when the occupancy state of thespace is unoccupied, the thermostat may reduce or even completelyeliminate the rate of outdoor airflow into the space. An unoccupiedspace has a reduced risk of infectious particles in the air infecting aperson, and the thermostat can be configured to reduce the rate ofoutdoor airflow into the space in response to the reduced risk. Reducingthe rate of outdoor airflow into the space saves energy, as the fan mayrun at a slower speed or for a shorter period of time and less outdoorair must be conditioned.

In addition or alternatively to the indirect indication of occupancyprovided by the CO₂ value in the space, the thermostat can be configuredto determine occupancy of the space by referencing an occupancy scheduleand/or the input of an occupant sensor in the space. In someembodiments, the thermostat can be configured to purge the space (i.e.,take in outdoor air and ventilate indoor air) prior to and/or afteroccupied states to achieve a clean air supply. The duration of the purgecan depend on the size of the space, the air change rate, apredetermined purge period, or other parameters sufficient to determinethe purge appropriately reduce the concentration of airborne pathogens.

Referring now to FIG. 9 , a drawing of a block diagram of a building 800with a thermostat 802 and HVAC equipment 738 is shown, according to someembodiments. The building 800 may include one or more indoor sensors822, and one or more outdoor sensors 824, one or more blower fans 806,and one or more ventilators 808.

The thermostat 802 includes a user interface 812 and can include thefeatures and provide the operations of control device 214 (e.g., FIGS.5-8 ) for the systems illustrated in FIGS. 1-4 or the building 800. Theuser interface 812 may be an interactive pixelated display (liquidcrystal display (LCD)) and touch screen that can display variableinformation to a user and receive an input from the user. The thermostat802 includes a temperature sensor 814 and an occupant sensor 816. Insome embodiments, the thermostat 802 incudes additional or fewersensors. While shown to include temperature sensor 814 and occupantsensor 816 as components of the thermostat 802, in some embodiments thesensors are external sensors communicably coupled to the thermostat 802.

The thermostat 802 is configured to receive inputs from user 818,external interrupt 820, indoor sensor 822, and outdoor sensor 824. Insome embodiments, the thermostat 802 is configured to generate controlsignals for HVAC equipment 738 via a wired or wireless communicationlink based on the inputs. In various embodiments, the thermostat 802generates control signals for the HVAC equipment 738 based on the indoorambient temperature (e.g., measured via an indoor ambient temperaturesensor), the outdoor temperature (e.g., measured via an outdoor ambienttemperature sensor), a temperature set point (e.g., set by a user via auser input on user interface 812), the indoor CO₂ value (e.g., measuredvia an indoor CO₂ sensor), the CO₂ setpoint (e.g., default setpoint setby an administer), and/or occupancy (e.g., determined by an occupancyschedule, occupant sensor, etc.) and provides the control signal to theHVAC equipment 738.

In some embodiments, the thermostat 802 includes a detachable unit whichprovides thermostat functions and can include various sensors, powercircuits, interfaces and other non-display components of a thermostat.The detachable unit may provide the control signals for the HVACequipment vie a three or four wire connection in some embodiments. Thedetachable unit may receive the control signals or data indicative ofthe control signals wirelessly or via a wired connection from userinterface 812 in some embodiments.

HVAC equipment 738 provides heated and/or cooled air to building 800 insome embodiments. Although described with respect to building 800,embodiments of the systems and methods described herein can be utilizedin a cooling unit or a heating unit in a variety of applicationsincluding commercial and/or residential HVAC units (e.g., AHU 402, rooftop units, etc.). In general, a building 800 includes refrigerantconduits that operatively couple an indoor unit to an outdoor unit ofair HVAC equipment 738. Indoor unit may be positioned in a utilityspace, an attic, a basement, and so forth. Outdoor unit is situatedadjacent to a side of building 800. Refrigerant conduits transferrefrigerant between indoor unit and outdoor unit, transferring primarilyliquid refrigerant in one direction and primarily vaporized refrigerantin an opposite direction. A furnace/boiler or heat pump of the airconditioner/heat pump of the HVAC equipment 738 is controlled to provideheat to the building 800. In some embodiments, thermostat 802 is incommunication with a network via a wired local network or wirelessnetwork.

The indoor sensors 822 can include temperature sensors, humiditysensors, CO2 sensors, occupant sensors, and volatile organic compound(VOC) sensors. In one embodiment, the indoor sensors 822 are located atmultiple points within the building 800. However, in some embodiments,one or more of the indoor sensors 822 may be integrated into the controldevice 214. The outdoor sensors 824 may also include temperaturesensors, humidity sensors, CO2 sensors, VOC sensors and the like.outdoor sensors 824 may further include weather sensors, light sensors,or other air quality sensors.

The blower fans 806 are configured to circulate air through the HVACequipment 738 and throughout the building 800. In some embodiments, theblower fans 806 may be used as supply fans for the HVAC equipment 738,(e.g. supplies air to the HVAC equipment 738). The ventilator 808 isconfigured to ventilate the air inside the building 800 to the outsideof the building 800. The ventilator 808 is further configured to bringoutside air into the building 800. This can provide fresh air into thebuilding 800, which may then be circulated by the blower fan 806, andused to control the air quality in the building 800. The ventilator 808may be a traditional ventilator, an energy recovery ventilator, a heatrecovery ventilator, or other applicable ventilator type.

The blower fan 806 and the ventilator 808 may be controlled to provideair quality enhancements within the building. In some embodiments, thecontrol device 214 can control the blower fan 806 and the ventilators808 to reduce the amount of energy used by the system by using outdoorair that meets one or more requirements as supply air without needing tocondition the outdoor air. The control device 214 may use data providedby the indoor sensors 822 and/or the outdoor sensors 824 to properlycontrol the blower fan 806 and the ventilators 808, as described herein.

Demand Control Ventilation

Turning now to FIG. 10 , a process 900 for providing demand controlventilation to a space is shown, according to some embodiments. Insystems with an economizer including both a blower fan 806 and aventilator 808, the ventilator 808 may be operated in conjunction withthe blower fan 806, based on certain conditions being met as describedbelow. In one embodiment, the process 900 is controlled by the controldevice 214. Specifically, the process 900 may be controlled by theventilation module 744 of control device 214. The process 900 may startat process block 902.

At process block 904, the control device 214 determines if the DemandControl Ventilation (DCV) feature for the control device 214 is enabled.In some embodiments, the DCV feature is enabled by a user via a userinput to the control device 214 (e.g., via user interface 702). In someembodiments, the control device 214 determines if DCV is enabled byreferencing a DCV object in a building management system. If the controldevice 214 determines the DCV is not enabled, the process 900 is shownto proceed to return process block 922.

If the control device 214 determines the DCV is enabled, process 900 isshown proceeding to process block 906 and the control device 214 mayobtain a CO₂ setpoint for a space. The CO₂ setpoint may be set by a uservia user interface 702 of control device 214. In some embodiments, theCO₂ setpoint is based on promulgated standards, guidelines, (e.g.,ASHRAE guidelines) for building safety. The CO₂ setpoint can be adiscrete value, but may also be a value range. For example, the CO₂setpoint may be 800-1000 ppm. As described above, the CO₂ setpoint canindirectly represent the occupancy levels in a space. A CO₂ setpoint mayalso be obtained by the control device 214 from a building managementsystem (BMS). While FIG. 10 is shown referencing a CO₂ setpoint andvalue, it should be understood that process 900 may refer to otherparameters in a space, (e.g., a VOC setpoint, pathogen concentration,carbon monoxide setpoint, etc.). One or more sensors 714 of controller214 may be configured to measure these parameters (e.g., air qualitysensor 720) for use in process 900 in place of the concentration of CO₂.

At process block 908, the control device 214 may determine if the CO₂value in a space is above the CO₂ setpoint. The control device 214 canmeasure the CO₂ value in a space using a CO₂ sensor (e.g., air qualitysensor 720) built into the control device 214. Still in otherembodiments, the control device 214 is connected to an external CO₂sensor (e.g., indoor sensor 822). The control device 214 may also beconnected to a BMS and receive the CO₂ value for the space via the BMS.As described above, in some embodiments other parameters aside from CO₂concentration are used, including the concentration of other gases,particles, pathogens, etc.

In some embodiments, when sampling the CO₂ value of a space the controldevice 214 is configured to generate an alarm on a display of thecontrol device 214 such as electronic display 706 when the CO₂ value ofthe space is above a critical threshold. A control device 214 connectedto a BMS can propagate the alarm to a supervisory device (e.g., BMScontroller 466). The CO₂ value can also be available to users andsupervisors via a BACnet interface of the BMS. In some embodiments, thecritical threshold is set by a user via user interface 702. For example.the control device 214 can be configured to generate an alarm if the CO₂value of the space is about 1100 ppm. In some embodiments, in additionto generating the alarm, the control device 214 can be configured toimmediately operate a ventilator in space in order to reduce theconcentration of CO₂ in the space.

If the CO₂ value for the space is determined to be above the CO₂setpoint, the process 900 may then activate the ventilator/economizerpriority control in process block 910. The normal control scheme of acontrol may control the operation of a ventilator/economizer for aspace. The DCV logic when enabled, and when it determines the CO₂concentration in a space is above the CO₂ setpoint, can be configured totake over control of the ventilator/economizer and give its commandspriority over those from the normal control scheme. For example, thenormal control scheme may direct the position of a damper in aneconomizer to 50%. The DCV may determine the CO₂ value is above the CO₂setpoint and prepare to ventilate a space, but to do so it needs to takecontrol of the damper position, and so it will activate control priorityensuring it can move the damper despite the control instructions fromthe normal control scheme.

After taking control priority, the control device 214 may determine ifthe outdoor air conditions are favorable for a demand controlventilation process at process block 912. As described above, the CO₂value of space can be an indirect measurement of the occupancy level ofa space, as well as the concentration of other pollutants and pathogensin a space. At process block 912 the control device 214 may determine ifthe CO₂ value is above the CO₂ setpoint that the concentration ofpathogens in the space is undesirable, and an air exchange taking inclean outdoor air would be favorable.

In some embodiments, the control device 214 may determine if outdoor airconditions are favorable by evaluating data from one or more sensors,such as air quality sensors 720, to determine an air quality of theindoor and air. In some embodiments, the control device 214 may obtainair quality data from the indoor sensors 822 and the outdoor sensors824. The condition of the outdoor air may be evaluated based on certainmeasurements, such as CO2 levels, VOC levels, pollen levels,temperature, humidity, etc. The control device 214 may determine thatthe outdoor air quality is favorable when one or more of themeasurements are below or above certain threshold values. For example,if the indoor air temperature is above the indoor air setpoint, and theoutdoor air is a lower temperature than the indoor air, the controldevice 214 may determine outdoor air conditions are favorable, as thelower temperature outdoor air can be used as free cooling for the spacewhile simultaneously assisting with the removal of pathogens due to theair exchange.

If the outdoor air condition is determined to be favorable at processblock 912, the process 900 may then determine if the space is occupiedat process block 914. In some embodiments, the control device 214 maydetermine the occupancy status of a space using occupancy module 750. Insome embodiments, the process 900 may not depend on the occupancy of thespace and may pass directly to process block 916.

The control device 214 can determine if the space is occupied based onan occupancy schedule. The occupancy schedule can be stored in controldevice 214 or provided to the control device 214 by a supervisorycontroller, for example a BMS connected to control device 214. Theoccupancy schedule may include scheduled periods of occupancy set by auser via a user interface of control device 214 (e.g., user interface702). In some embodiments, the control device 214 determines if space isoccupied according to the input from an indoor sensor 822 such as anoccupant sensor provided in the space. The occupant sensor may be anear-field communications (NFC) sensor, a radio frequency identification(RFID) sensor, a Bluetooth sensor, a capacitive proximity sensor, abiometric sensor, an infrared (IR) sensor, or any other sensorconfigured to detect the presence of a person or device.

If the space is determined to be occupied at process block 914, theprocess 900 begins ventilating the space by running the ventilator(e.g., ventilator 808) at a fast rate of outdoor airflow as configuredby a user at process block 916. At process block 916, the control device214 may, for example, control the position of a damper in the HVACequipment 738 to open the space to the outdoor air and take the outdoorair into the space. In some embodiments, the control device 214 may alsooperate a fan (e.g., fan 806) to draw the outdoor air through the damperand into the space. The rate of outdoor air flow into the space candepend on the position of one or more dampers, the speed of the fan, andthe indoor and outdoor temperatures. In some embodiments, the rate ofoutdoor airflow is set by a user via user interface 702. A user may seta desired fast rate of outdoor air flow by providing a user inputindicating a desired airflow rate, damper position, and/or fan speed. Insome embodiments, the airflow rate is configured by a supervisory deviceof a BMS.

Returning to process block 914, if the control device 214 determines thespace is not occupied, the process 900 begins ventilating the space byrunning the ventilator at a second, reduced rate of outdoor air flow into the space at process block 918. Exchanging the indoor air withoutdoor air can be energy intensive as requires running one or more fansand may require the HVAC equipment 738 to condition the outdoor airbefore supplying it to the space, and the rate of outdoor air flowitself can contribute to this cost. When a space is determined to beunoccupied and the pathogens in a space (as indicated by the CO₂ levels)are no longer interacting with any occupants, the need for demandcontrol ventilation is reduced. Accordingly, the control device 214 canbe configured to reduce the rate of outdoor airflow into a space whenthe space is determined to be unoccupied to save energy and money. Insome embodiments, the rate is reduced to zero and no exchange takesplace when a space is unoccupied. Still, in other embodiments the rateis reduced to a non-zero value that is simply less than the rate ofoutdoor air flow when the space is determined to be occupied asconfigured by the user. A user/supervisory device may set, at a priorpoint in time, a desired airflow rate as described above.

In some embodiments, it may be beneficial to engage a demand controlventilation feature such as process 900 even when a space is unoccupiedas a precautionary measure to ensure a space is well-ventilated when anoccupant does arrive. A damper remaining entirely closed when a space isunoccupied may create a situation where before CO₂ levels, andrelatedly, pathogen levels in a space are reduced by the typicaloperation of HVAC equipment in space, are brought below a desired levelan occupant enters the space and encounters the space with its elevatedCO₂ and pathogen concentrations. By allowing a space to continue toprovide demand control ventilation even when unoccupied, even at areduced rate, the likelihood of this scenario is reduced.

After either process block 916 or process block 918, process 900 returnsto process block 908 and determines if the CO₂ value in a space is stillabove the CO₂ setpoint. In some embodiments, on returning to processblock 916 the control device 214 determines if the CO₂ value is not justbelow the CO₂ setpoint, but at a certain value i.e., an acceptable CO₂value before proceeding. For example, the CO₂ setpoint may be 800 ppm,and the control device 214 is configured to turn proceed to processblock 920 until the CO₂ value of the space of the space is below anacceptable CO₂ value of 400 ppm. Process 900 then proceeds to processblock 922 and returns to initial process block 902 in process 900.

Referring still to process block 908, if the CO₂ value of the space isstill above the setpoint, process 900 proceeds to process block 910 asdescribed above. In some embodiments, the control device 214 isconfigured to ventilate a space for a predetermined amount of timebefore checking the CO₂ value of the space again at process block 908.For example, a user may set a default purge time of one hour, and oncethe CO₂ value is initially determined to be above the CO₂ setpoint thepurge duration must elapse before the control device 214 may end thepurge and shut off the ventilator 808. The purge duration may depend onthe air exchange rate. The air exchange rate is the number of times theair is replaced in a space for a period of time (e.g., air changes perhour). The air exchange rate for a space is represented by thevolumetric flow rate of air into the space divided by the volume of thespace. The thermostat 802 can calculate the air exchange rate for sspace, and use the air exchange rate to calculate how long the purgetime must be for a desired number of air changes. For example, thecontrol device 214 can be configured to maintain running the ventilatorat process blocks 916 and 918 until three air changes in the space havebeen completed. Relatedly, a control device 214 may be configured toperform a maximum number of air changes in a day. If the maximum numberof air changes is obtained, the control device 214 may then beconfigured to check the CO₂ value and determine if the purge can end.

If at process block 908 the control device 214 determines the CO₂ valueof the space is not above the CO₂ setpoint, the process 900 proceeds toprocess block 920 and releases ventilator/economizer control, if active.For example, if process 900 has not previously proceeded to processblock 910 ventilator/economizer priority for DCV may not be activated.If process 900 has activated ventilator/economizer control at processblock 910, then at process block 920 that control is deactivated andcontrol of the ventilator/economizer passes back to the normal controlscheme. In some embodiments, control may pass to another schemeindicating it has control priority (e.g., an epidemic controlventilation scheme). In some embodiments, the control device 214 isconfigured to turn off the ventilator at process block 920. Afterreleasing control of the ventilator/economizer at process block 920,process 900 proceeds back to process block 904.

At any point in process 900, an interrupt/override may be provided tocontrol device 214 which may indicate that control device 214 shouldterminate process 900. For example, the interrupt may be an externalinterrupt as described below.

Epidemic Control Ventilation

Turning now to FIG. 11 , a process 1000 for purging a zone of pathogensthrough ventilation is shown, according to an exemplary embodiment. Insome situations, it is preferable to implement supplemental measures forventilating a space in addition to or alternatively to the demandcontrol ventilation features discussed above. For example, a thermostatmay use CO₂ levels as a proxy for the occupancy level of a space (andtherefore the pathogen load of a space) but this is an indirect methodthat may in some cases underestimate the pathogen load. To provide awell-ventilated space regardless of the CO₂ levels (or the concentrationof other measured parameters such as VOC levels, pathogen load, etc.) insome embodiments a thermostat (e.g., control device 214, thermostat 802,etc.) may be configured to ventilate a zone (i.e., purge a zone) priorto and/or post occupancy. For example, a thermostat may be configured toramp up a damper from a minimum position to a purge damper position(e.g., 80%, 90%, 100%, or any other percentage) for a purge periodbefore and/or after occupancy of the space. The purge period may be adefault time period, based on a user input, or depend on a calculatedair exchange rate and desired number of air changes for a space. Forexample, a purge duration may persist such that three air changes in aspace are performed. Pre- and post-occupancy purges reduce the risk ofan occupant from a first occupied period passing contagions to anoccupant in a later occupied period. The air exchange rate may indicatethe rate of outdoor airflow in a space, and can depend on the damperpositions and the speed of one or more fans in the HVAC equipment.

In some embodiments, the purge damper position is adjusted based on atemperature of the indoor space and/or the temperature of the outdoorair. In some embodiments, purge damper position can be actively adjustedbased on the rate of change of the temperature of the space. The rate ofchange of the temperature in a space is dependent on the temperature ofthe space, the temperature of the outdoor air, the damper position, theflow rate of air into the space, and the temperature characteristics ofthe space's surrounding environment. For example, on cold days when thetemperature of the outdoor air is less than the temperature of theindoor air, as the space is purged the temperature in the space willstart to decrease. The damper position can be actively adjusted duringthis process. In some embodiments, the purge damper position is adjustedbased on the outdoor air temperature. In some embodiments, the purgedamper position is adjusted to ensure the indoor temperature meets oneor more thresholds (i.e., the rate of change is within a predeterminedlimit, the temperature of the space is maintained above a predeterminedthreshold, etc.). For example, on warmer days the damper position duringa purging operation can be actively adjusted to ensure the spacetemperature remains below a predetermined threshold and/or to ensurethat the rate of change of the temperature in the space is below apredetermined threshold. In some embodiments, a user can set a minimumpurge damper position. For example, when the damper position is beingactively controlled based on the temperature of the space, the damperposition can be limited to be at least above a certain percentage. Thislower limit can be set by a user to ensure that during a purge operationenough air is still ventilated. In some embodiments, the purge damperposition itself can be preset by a user of the thermostat. For example,a user can set the purge damper position to 80%, such that during apurge cycle the damper is opened to 80%.

In some embodiments, a thermostat with epidemic control ventilation canadjust the control of ventilation in a room based on the fact that preand/or post occupancy purges are implemented. For example, a system withpre-occupancy purges may otherwise operate in a minimum ventilation modeduring an unoccupied mode as the space will be purged before occupancyin a pre-occupancy purge and increased ventilation prior to the purgemay be inefficient. In some embodiments, the system may also run in aminimum ventilation mode during an occupied state based on pre- and/orpost occupancy purges.

When implementing pre- and/or post occupancy purges according to process1000, in systems including both a blower fan 806 and a ventilator 808,the ventilator 808 may be operated in conjunction with the blower fan806, based on certain conditions being met as described below. In oneembodiment, the process 1000 is controlled by as control device 214.Specifically, the process 1000 may be controlled by the purge module 746of control device 214. The process 1000 may start at process block 1002.In some embodiments, process 1000 requires measurements of the CO₂ valuein a space (e.g., from indoor sensor 822), a damper feedback valueindicating its position (e.g., from one or more dampers 416-420, anoutside air temperature value (e.g., from outdoor sensor 824), a supplyair temperature value (e.g., from sensors in AHU 106), and a CO₂setpoint. In some embodiments, process 1000 includes receivesmeasurements of additional parameters of a space from air sensors (e.g.,indoor sensor 822, outdoor sensor 824, such as a concentration ofasbestos, biological pollutants, carbon monoxide, nitrogen dioxide,natural gas, and/or the viral or pathogen load of a space, amongst othermeasurable air quality parameters. Process 1000 may use these values,amongst others, to facilitate pre- and/or post occupancy purges ofzones.

Before running the purge logic of process 1000, the control device 214can be configured to request a user set a minimum ventilation positionfor a damper (e.g., in an economizer-type air handling unit such AHU402) between 0% and 100%. The minimum ventilation position may applyduring both the occupied and unoccupied mode for the space. The minimumventilation position may be used as a default position that the damperis returned to after a purge. In some embodiments, a user may also inputa desired purge duration and/or a desired number of air changes.

At process block 1004, the control device 214 obtains an occupancyschedule for the space. The occupancy schedule indicates when a space isset to an occupied mode and unoccupied mode. In some embodiments, theoccupancy schedule is provided by a BMS connected to the control device214 (e.g., by BMS controller 466). In some embodiments, the occupancyschedule is provided by a user via user interface 702. The occupancyschedule may take precedent over other indications of occupancy such asfrom an occupant sensor. Occupancy may also be determined by acombination of inputs from an occupancy schedule and an occupant sensor.For example, the occupancy schedule may indicate an unoccupied mode fora space starts at 10 PM, but the occupant sensor may indicate that fromat 10:00 PM the space is still occupied. Based on the input from theoccupant sensor, the control device 214 can determine that despite thescheduled unoccupied mode the space is still occupied, and delay apost-occupancy purge until the occupancy schedule and the occupancyschedule agree the space is unoccupied. In one embodiment, if nooccupancy schedule is available, the control device 214 can trigger analarm and disable the epidemic purge ventilation.

In some embodiments, process 1000 can take priority over other processesthat control the ventilation in a space. For example, a thermostatconfigured with a demand control ventilation process (e.g., process 900)as described above may also implement an epidemic control ventilationprocess such as process 1000. In some embodiments, process 1000 maysupersede process 900 for control of ventilation in a room. Still inother embodiments, the DCV control may supersede the control indicatedin process 1000.

At process block 1006, the control device 214 calculates thepre-occupancy purge state time based on the purge duration and theoccupancy schedule. The purge duration may be received from a userinput, from a BMS/supervisory device, or be a default value stored inthe control device 214. In some embodiments, the control device 214calculates the purge duration based on a desired number of air changesand measured/calculated air exchange rate for space. A user can set thepurge duration indirectly by selecting a desired number of air changesin a zone that the purge should complete before the purge ends. In suchembodiments, the control device 214 can be configured to calculate howlong the HVAC equipment will take to complete the requested number ofair changes and calculate the pre-occupancy purge start timeaccordingly.

In some embodiments, the pre-occupancy purge start time is the latesttime at which the purge duration must start for the purge to completebefore the beginning of the first occupied period as indicated by theoccupancy schedule. It can be calculated by subtracting the purgeduration from the start time of the first occupied period. For example,an occupancy schedule for a day may indicate the first occupied periodfor the space begins at 8:00 AM. With a purge duration of 4:00 hours,the control device 214 can calculate the pre-occupancy purge start timeto be 4:00 AM. The control device 214 may calculate the pre-occupancypurge start time day-by-day. That is, if the occupancy schedule is aweekly schedule, the control device may partition the schedule intodaily schedules, and calculate pre-occupancy purge start times for eachday, such that each day the purge begins at the latest time at which itcan be completed before the beginning of the occupied period for thatday.

After calculating the pre-occupancy purge time, process 1000 proceeds toprocess block 1008 and initiates the preoccupancy purge at thecalculated time. For example, with a purge duration of 1 hour, thecontrol device 214 may initiate a pre-occupancy purge at 7:00 AM basedon a schedule indicating the occupied period starts at 8:00 AM (i.e.,for the last hour of the unoccupied period before the first occupiedperiod of that day). During the pre-occupancy purge the control device214 can modulate the position of one or more dampers (e.g., dampers416-420) in HVAC equipment 738 from its current position to a purgedamper position for the duration of the purge. The purge damper positionmay be a preset position (e.g., 80%, 90%, 100%, etc.). A user may setthe purge damper position. The purge damper position may be based on atemperature of the space and/or a rate of change of the temperature ofthe indoor space. A user may additionally set a minimum purge damperposition the damper position is not to fall below when being activelycontrolled based on temperature. The purge The purge includes exchangingindoor air for outdoor air to ventilate a space and reduce theconcentration of one or more air quality parameters.

After initiating the purge at the calculated time at process block 1008,the control device 214 can continue purging the space for the purgeduration, if there is no override or interrupt. For example, the controldevice 214 may receive a signal from an external interrupt 752indicating control device 214 should stop its control scheme includingdisable all control outputs. In some embodiments, the interrupt may bereceived from a user. Still in other embodiments, the interrupt may bereceived from a supervisory device in a BMS. In some embodiments, theinterrupt may be based on an outdoor air quality. In some embodiments,the control device 214 can determine if outdoor environmental conditionsare favorable for ventilation during process 1000. For example, thecontrol device 214 may determine the outdoor environmental conditions asdescribed above with reference to process block 910.

If an override/interrupt is received, or if the purge duration haselapsed, the control device 214 may cease the pre-occupancy purge andreturn the position of one or more dampers from the purge damperposition to the position indicated by the control device 214's normalcontrol scheme at process block 1012. In some embodiments, the controldevice 214 returns control of the dampers to other processes, such as ademand control ventilation process, and the damper is positioned asrequired by such processes. In one embodiment, the epidemic controlventilation represented in process 1000 performs only pre-occupancypurges, and after process block 1012 proceeds to return at process block1022. In another embodiment, the purge logic proceeds from process block1004 directly to process block 1014 and performs only post-occupancypurges according to process blocks 1014-1020. Still in anotherembodiment, the control device 214 may include both pre and postoccupancy purges. A user may indicate via a user interface (e.g., userinterface 702) whether control device 214 should perform pre-occupancypurges, post-occupancy purges, or both. In some embodiments, the optionto enable epidemic control ventilation (including pre and/or postoccupancy purges) is exposed to a BMS (e.g., to BMS controller 466)through a point object enabling remote activation and deactivation ofthe feature by a BMS manager.

In embodiments with post-occupancy purge, at process block 1014 theprocess 1000 can calculate the post-occupancy purge start time from thepurge duration and the occupancy schedule. In some embodiments, thepost-occupancy purge start time is the end of the last occupied periodfor the schedule period as indicated by the occupancy schedule (i.e.,the beginning of the last unoccupied period for the schedule).

Epidemic control ventilation may also affect other characteristics of aspace. For example, ventilation can raise or lower the relative humidityin a space. A thermostat such as control device 214 performing epidemiccontrol ventilation can monitor the relative humidity of the space andtrigger an alarm when it exceeds a preset range (e.g., 40%-60% RH). Insome embodiments, the control device 214 can delay or cancel anotherwise scheduled pre and/or post occupancy purge if it determinesoutside air conditions are unfavorable. Unfavorable conditions mayinclude the delta between the outside air temperature and the indoor airtemperature exceeding a predetermined threshold, the outside airtemperature being too low or too high, the outside air RH being too lowor too high, the air quality of the outside air is poorer than the airquality of the inside air, etc.

External Interrupt

Referring generally to FIG. 12 , a thermostat, such as control device214 may operate to control the building equipment in a space accordingto a control scheme. The control scheme may include logic for providingone or more command instructions for building equipment to control theenvironment of a space. In some embodiments, the thermostat may receivean external interrupt signal. In some embodiments, in response to theexternal interrupt signal the thermostat may be configured to stop thethermostat control scheme, and thereby cease the provision of commandinstructions to building equipment. In some embodiments, though thecontrol scheme is stopped, the thermostat may continue to receive inputsignals and process other forms of communication, such as communicatingwith a BMS and otherwise operate normally. For example, on receiving aninterrupt signal, a thermostat may be configured to stop controlling themovement of a damper, but to still receive a temperature signal from atemperature sensor and calculate a damper position based on the signal.

In some embodiments, a thermostat such as control device 214 may includeone or more binary input (BI) terminals for receiving inputs and addingadditional features to the system. The BI terminals can includeconfigurable BIs accessible to a user. Based on the status of a givenBI, the thermostat can be configured to perform a control action. Thecontrol action may include disabling one or more outputs of thethermostat (e.g., control instructions for HVAC equipment), setting anoccupancy value, initiating an alert, etc. BIs can include windowsensors, door sensors, motion sensors, proximity sensors, fan on/offstatus inputs, dirty filter inputs, temporary occupancy inputs, directoccupancy override inputs, etc. In one embodiment, the sensors can bevirtual sensors whose value can be controlled by a user of thethermostat.

In some embodiments, the BI is configured as an external interrupt. Asdescribed above, the external interrupt may act as trigger for thecontrol device 214 and receive either a high or low signal (e.g., trueor false, activate or inactive, etc.), such that the control device 214is configured to disable its control scheme when the external interruptis triggered (e.g., signal goes high, signal goes low). In someembodiments, the control scheme is stopped, but the rest of the controldevice 214 remains in operation. That is, the thermostat may operate inan otherwise normal fashion, receiving inputs and monitoring a space,and communicating with other pieces of equipment, and in generalperforming such associated determinations according to its programming,except the thermostat will not provide control signals for controllingHVAC equipment. The associated determinations may include controlsignals for building equipment (e.g., damper positions, fan states,etc.), setpoints for a space, occupancy states, etc. and any other valueor calculation that the thermostat configured to determine. In otherwords the thermostat can monitor and log the environmental conditions ofthe space as usual, and communicate information to a BMS or anotherdevice, but all output control signals for controlling the operation ofHVAC equipment typically provided according to the control scheme areotherwise disabled.

An external interrupt can be initiated by both physical or virtualswitches. In some embodiments, multiple switches are connected as anexternal interrupt, the activation of any of which would halt alloutputs of the thermostat. In some embodiments, the external interruptis presented to a user via user interface of a thermostat (e.g., userinterface 702, 812).

Turning now to FIG. 12 , a process 1100 for providing an externalinterrupt to an HVAC system is shown, according to an exemplaryembodiment. In one embodiment, the process 1100 is controlled by thecontrol device 214. Specifically, the process 1100 may be controlled bythe external interrupt module 748 of the control device 214. The process1100 may start at process block 1102 for external interrupt logic.

At process block 1104, the control device 214 determines if an externalinterrupt was trigged. As described above, the control device 214 mayinclude one or more binary inputs (BIs) that may be configured to act asan external interrupt. An external interrupt signal may be provided byone or more switches and/or sensors in a space (e.g., external interrupt758, external interrupt 820, etc.) or by virtual switches. For example,the external interrupt can be connected to a temperature-controlledrelay configured to sense the temperature of a heating coil exposed tooutside air. The relay may activate when the temperature of the heatingcoil falls below a minimum threshold indicating that the heating coilmay be frozen. In order to avoid further damage to the heating coil byattempting to operate it while frozen, the control device 214 mayreceive the signal from the temperature-control relay at the externalinterrupt (e.g., the binary input configured as an external interrupt)and stop the control scheme of the control device 214, ensuring heatingcoil is not operated until the external interrupt is no longer present.In some embodiments, the external interrupt is triggered (i.e.,activated) when the binary input (BI) value is driven high. Still inother embodiments the interrupt is triggered when the value is drivenlow. If the control device 214 determines the external interrupt is nottrigged, process 1100 can return to process block 1112.

If the control device 214 determines the external interrupt istriggered, the thermostat proceeds to stop the thermostat controlscheme, but continue to monitor all inputs and maintain communicationsat process block 1106. Stopping the control scheme may include ceasingto provide control outputs including control signals/commandinstructions to equipment operated by the thermostat. While outputs aredisabled, the thermostat may still be active and otherwise receivesensor signals and maintain communications without interrupt. Byallowing a thermostat to be active despite disabling output control, theexternal interrupt can make equipment safe for service and repairwithout the need for a cold start when repairs are completed. Instead,the interrupt can be deactivated and the thermostat outputs restored anddirected as indicated by the still-running control scheme. While processblock 1106 is shown to proceed directly after an external interrupt istrigged in process block 1104, in some embodiments, the externalinterrupt is delayed by a period of time before the control scheme isstopped. For example, a 30-second delay may be activated and then thecontrol scheme is stopped.

At process block 1108, the thermostat determines if the externalinterrupt is still present. If the thermostat determines the externalinterrupt is still present, then process block 1108 can repeat. If thethermostat determines the external interrupt is no longer present, thenat process block 1112 the control device 214 can resume the controlscheme and therefore resume controlling the environment of the space. Atprocess block 1114 the external interrupt logic returns.

Configuration of Exemplary Embodiments

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.). For example, the position of elements may bereversed or otherwise varied and the nature or number of discreteelements or positions may be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure. The order or sequence of any process or method stepsmay be varied or re-sequenced according to alternative embodiments.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions and arrangement of the exemplaryembodiments without departing from the scope of the present disclosure.

The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a machine, the machine properly views theconnection as a machine-readable medium. Thus, any such connection isproperly termed a machine-readable medium. Combinations of the above arealso included within the scope of machine-readable media.Machine-executable instructions include, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing machines to perform a certain function orgroup of functions.

Although the figures show a specific order of method steps, the order ofthe steps may differ from what is depicted. Also two or more steps maybe performed concurrently or with partial concurrence. Such variationwill depend on the software and hardware systems chosen and on designerchoice. All such variations are within the scope of the disclosure.Likewise, software implementations could be accomplished with standardprogramming techniques with rule based logic and other logic toaccomplish the various connection steps, processing steps, comparisonsteps and decision steps.

What is claimed is:
 1. A controller for controlling heating,ventilation, or air conditioning (HVAC) equipment in a building, thecontroller comprising: a processing circuit comprising one or morememory devices coupled to one or more processors, the one or more memorydevices configured to store instructions thereon that, when executed bythe one or more processors, cause the one or more processors to: receivean occupancy schedule indicating at least one of a first occupied periodor a last unoccupied period for a space in the building for a scheduleperiod; receive a user input indicating the space should be purged basedon occupancy; select, based on the user input, at least one of apre-occupancy purge mode or a post-occupancy purge mode; control theHVAC equipment to ventilate the space for a purge duration prior to thebeginning of the first occupied period in response to selecting apre-occupancy purge mode; and control the HVAC equipment to ventilatethe space for the purge duration at the beginning of the last unoccupiedperiod in response to selecting a post-occupancy purge mode.
 2. Thecontroller of claim 1, wherein the controller is a thermostat positionedin the space.
 3. The controller of claim 1, wherein the controller iscommunicably coupled to a building management system (BMS) for thebuilding, and receives the occupancy schedule from the BMS.
 4. Thecontroller of claim 1, the one or more memory devices are furtherconfigured to store instructions thereon that, when executed by the oneor more processors, cause the one or more processors to: in response toselecting a pre-occupancy purge mode, calculate a pre-occupancy purgestart time based on a purge duration and the occupancy schedule, whereinthe pre-occupancy purge start time is the latest time ventilation canbegin and the purge duration elapse before the beginning of a firstoccupied period; control the HVAC equipment to ventilate the space forthe purge duration starting at the pre-occupancy purge start time priorto the end of the first unoccupied period in response to selecting apre-occupancy purge mode; and control the HVAC equipment to ventilatethe space for the purge duration starting at the beginning of the lastunoccupied period in response to selecting a post-occupancy purge mode.5. The controller of claim 1, wherein the HVAC equipment comprises anair economizer including a damper configured to control the rate ofoutdoor airflow into the space, wherein the one or more memory devicesare further configured to store instructions thereon that, when executedby the one or more processors, cause the one or more processors tocontrol the HVAC equipment to ventilate the space by modulating theposition of the damper.
 6. The controller of claim 5, wherein the one ormore memory devices are further configured to store instructions thereonthat, when executed by the one or more processors, cause the one or moreprocessors to control the HVAC equipment to ventilate the space bydriving the damper to a 100% open position for the purge duration beforereturning the damper to a minimum ventilation position at the end of thepurge duration.
 7. The controller of claim 1, the one or more memorydevices are further configured to store instructions thereon that, whenexecuted by the one or more processors, cause the one or more processorsto: receive outdoor air data indicative of at least one of temperature,pressure, or humidity of air outside the building from an outdoorenvironmental sensor; determine, based on the outdoor air data, anoutdoor air quality of the outdoor air; and control the HVAC equipmentto ventilate the space based on the occupancy schedule and the outdoorair quality.
 8. The controller of claim 7, the one or more memorydevices are further configured to store instructions thereon that, whenexecuted by the one or more processors, cause the one or more processorsto: select either a purge mode or a normal mode based on the outdoor airquality; and control the HVAC equipment to ventilate the space based onthe occupancy schedule, the outdoor air quality, and the selected mode,wherein the HVAC equipment provides outdoor air to the space in responseto selecting the purge mode, and wherein the HVAC equipment providesreturn air to the space in response to selecting a normal mode.
 9. Thecontroller of claim 1, the one or more memory devices are furtherconfigured to store instructions thereon that, when executed by the oneor more processors, cause the one or more processors to: receiveoccupancy data from an occupant sensor configured to detect a presenceof an occupant in the space; determine, based on the occupancy data, ifthe space is occupied at the beginning of the last unoccupied periodindicated by the occupancy schedule; and delay, until the occupancy dataindicates the space is unoccupied, controlling the HVAC equipment toventilate the space for the purge duration at the beginning of the lastunoccupied period in response to selecting a post-occupancy purge mode.10. The controller of claim 1, the one or more memory devices arefurther configured to store instructions thereon that, when executed bythe one or more processors, cause the one or more processors to: receivethe IAQ value from an environmental sensor configured to provide anindoor air quality (IAQ) value indicative of a concentration of at leastone of a pollutant or a pathogen in a space in the building; determineif the IAQ value in the space is above an IAQ setpoint for the space;determine an occupancy status for the space; and control the HVACequipment to ventilate the space with outdoor air at a flowrate inresponse to determining that the IAQ value is above the IAQ setpoint,such that the flow rate when the occupancy status of the space isunoccupied is less than the flow rate when the occupancy status of thespace is occupied.
 11. A method for operating a controller for heating,ventilation, or air conditioning (HVAC) equipment in a building, themethod comprising: receiving an occupancy schedule indicating at leastone of a first occupied period or a last unoccupied period for a spacein the building for a schedule period; receiving a user input indicatingthe space should be purged based on occupancy; selecting, based on theuser input, at least one of a pre-occupancy purge mode or apost-occupancy purge mode; controlling the HVAC equipment to ventilatethe space for a purge duration prior to the beginning of the firstoccupied period in response to selecting a pre-occupancy purge mode; andcontrolling the HVAC equipment to ventilate the space for the purgeduration at the beginning of the last unoccupied period in response toselecting a post-occupancy purge mode.
 12. The method of claim 11,wherein the controller is communicably coupled to a building managementsystem (BMS), the method further comprising receiving the occupancyschedule from the BMS.
 13. The method of claim 11, further comprising:in response to selecting a pre-occupancy purge mode, calculating apre-occupancy purge start time based on a purge duration and theoccupancy schedule, wherein the pre-occupancy purge start time is thelatest time ventilation can begin and the purge duration elapse beforethe beginning of a first occupied period; controlling the HVAC equipmentto ventilate the space for the purge duration starting at thepre-occupancy purge start time prior to the end of the first unoccupiedperiod in response to selecting a pre-occupancy purge mode; andcontrolling the HVAC equipment to ventilate the space for the purgeduration starting at the beginning of the last unoccupied period inresponse to selecting a post-occupancy purge mode.
 14. The method ofclaim 11, wherein the HVAC equipment comprises an air economizerincluding a damper configured to control the rate of outdoor airflowinto the space, the method further comprising controlling the HVACequipment to ventilate the space by modulating the position of thedamper.
 15. The method of claim 14, further comprising controlling theHVAC equipment to ventilate the space by driving the damper to a presetpurge damper position for the purge duration before returning the damperto a minimum ventilation position at the end of the purge duration. 16.The method of claim 11, further comprising: receiving outdoor air dataindicative of at least one of temperature, pressure, or humidity of airoutside the building from an outdoor environmental sensor; determining,based on the outdoor air data, an outdoor air quality of the outdoorair; and controlling the HVAC equipment to ventilate the space based onthe occupancy schedule and the outdoor air quality.
 17. The method ofclaim 16, further comprising: selecting either a purge mode or a normalmode based on the outdoor air quality; and controlling the HVACequipment to ventilate the space based on the occupancy schedule, theoutdoor air quality, and the selected mode, wherein the HVAC equipmentprovides outdoor air to the space in response to selecting the purgemode, and wherein the HVAC equipment provides return air to the space inresponse to selecting a normal mode.
 18. The method of claim 11, furthercomprising controlling the HVAC equipment to ventilate the space bydriving the damper to a purge position for the purge duration beforereturning the damper to a minimum ventilation position at the end of thepurge duration, wherein the purge position is based on at least one of atemperature of the space in the building a temperature of outdoor airused to ventilate the space.
 19. The method of claim 11, furthercomprising: receiving occupancy data from an occupant sensor configuredto detect a presence of an occupant in the space; determining, based onthe occupancy data, if the space is occupied at the beginning of thelast unoccupied period indicated by the occupancy schedule; anddelaying, until the occupancy data indicates the space is unoccupied,controlling the HVAC equipment to ventilate the space for the purgeduration at the beginning of the last unoccupied period in response toselecting a post-occupancy purge mode.
 20. The method of claim 11,further comprising: measuring an indoor air quality (IAQ) valueindicative of a concentration a concentration of at least one of apollutant or a pathogen in a space in the building; determining if theIAQ value in the space is above a IAQ setpoint for the space;determining an occupancy status for the space; and controlling HVACequipment in the HVAC system to ventilate the space with outdoor air ata flowrate in response to determining that the IAQ value is above theIAQ setpoint, such that the flow rate when the occupancy status of thespace is unoccupied is less than the flow rate when the occupancy statusof the space is occupied.